It is well known to provide pumps which, when attached to a suitable reservoir of liquid, are capable, upon actuation of the pump, of expelling a foamed product from the outlet of the pump. Such pumps are well known and widely used to dispense a variety of products.
In general, they operate by attaching a pump to the neck of a container which serves as a reservoir for the liquid material which can take many forms, such as, soaps, lotions, etc. These pumps operate so that upon actuation of the pump a predetermined amount of liquid is drawn from the container or reservoir, mixed with air and expelled through a nozzle attached to one end of the pump. The mixing with air causes the material to be converted into a foam and such foam is then dispensed onto the hand of the user in the case of soap or lotion, for example.
Examples of patents dealing with pumps of this general type can be found in Banks U.S. Pat. No. 5,445,288; van der Heijden U.S. Pat. No. 6,053,364; Banks U.S. Pat. No. 6,082,586 and van der Heijden U.S. Pat. No. 6,220,483.
It has been found that these pumps are generally adequate for the purposes for which they were developed. The more conventional manner of distributing the material from the container is to set the container upright so that the pump extends upwardly from the container. However, it is often the case that a residue of foam remains on the nozzle and ultimately drips off. In the event there is a dripping problem, fairly complex valving arrangements have been utilized at the outlet or nozzle end of the pump or the pump has been designed so as to create a “suck-back” feature which pulls the residue back into the nozzle. Such modifications, however, add to development and pump costs.
This problem is particularly acute when the container is inverted and the pumping action takes place from beneath the container. This is a common practice wherein a replaceable container or reservoir is inverted and mounted in a dispenser which, in many instances, is mounted on a wall or other vertical surface with the nozzle and the pump itself projecting downwardly.
In any event, when a foam producing pump is operated in this fashion the pump, after exhausting its normal liquid pumping or drawing function, does not fully exhaust the foam stream particularly at the outlet or nozzle of the pump so that some of the foam stream typically hangs on the outlet at the end of the stroke and eventually, of course, will revert to its liquid form and drip. Dripping in pumps of this general nature and in pumps of this particular nature as well are objectionable because they are messy, unsightly and require maintenance to clean them up.
Accordingly, production of a foam producing pump of the type above-described which has an anti-drip feature becomes one object of this invention.